1. Field of the Invention
The present invention involves an optical switch, and particularly relates to a mechanical optical switch with rotatable reflecting means.
2. Description of Related Art
Optical switches are divided into two types. One is mechanical type and the other is non-mechanical type. In principle, the mechanical type optical switches have a number of advantages over other forms of optical switches in such applications where switching speed is not important. Mechanical type optical switches offer low insertion losses, a high degree of immunity against backscattering of light from the switch back down the input fiber, low cross-talk, and insensitivity to wavelength of light.
An elementary mechanical switch is operated by moving an input fiber relative to a plurality of output fibers. The simplest scheme is a xe2x80x9cbutt-couplingxe2x80x9d scheme in which the input fiber is moved to be selectively aligned with one of a plurality of output fibers by a motor. This kind of optical switch is limited in switching channels and has a bulky configuration and very slow switching speed.
Another kind of mechanical switch 40, as disclosed in U.S. Pat. No. 5,841,917 and shown in FIG. 7, includes an input port plate 41, an output port plate 42, and an array of reflectors 44 movably mounted on a base 43 and electrically connected to a control element 45. Each reflector 44 is connected to a driving post 48 which is mounted to a substrate 46 and moved by the control element 45. An input light beam 47 coming from a path 41a of the input port plate 41 is reflected by one of the reflectors 44 to leave the switch 40 from a corresponding path 42a of the output port plate 42. The reflectors 44 are selectively moved, via the corresponding driving posts 48, to protrude upwards out of or retract downwards into the base 43 thereby selectively reflecting the input light beam 47. Although the switching speed is higher than other mechanical optic switches discussed above, the switch 40 is still bulky and performs a complicated operation.
FIG. 8 shows another kind of mechanical switch 50 disclosed in U.S. Pat. No. 6,091,867. The switch 50 employs a plurality of reflecting elements 52, 54 having variable light transmission to achieve the switching function thereof. Each reflecting element 52 (54) may reflect an incident beam from an input port 51 to an output port 53 (55) or acts as a transmitter to pass the incident beam through. Whether the reflecting elements 52, 54 function as mirrors or transmitters depends on the application of control stimulus thereonto, such as medium transmissivity-modifying voltages. Such a design increases difficulty in manufacturing requirements and costs involved at the same time. This adversely offsets its advantages of a possible higher switching speed.
An object of the present invention is to solve the problems discussed above for providing an optical switch having a simple structure, small size, low costs and easy to operate.
In accordance with one aspect of the present invention, an optical switch comprises a light transmitting/receiving sub-assembly and a reflecting means facing each other. The light transmitting/receiving sub-assembly and the reflecting means are rotatable relative to each other between first and second positions. The relative rotation therebetween is realized by a motor rotating either one of the light transmitting/receiving subassembly and the reflecting means with respect to the other. The invention was filed with the Disclosure Document No. 482,438 dated Nov. 9, 2000 in an earlier time.
In an embodiment, the reflecting means comprises two reflecting strips perpendicular to each other. The reflecting strips may be integratively formed or coated on a circular disk. The two reflecting strips may also be separative and be connected with each other by the disk.
One of the reflecting strips consists two pairs of reflecting surfaces which are arranged to be 90-degree angled to each other, each pair forming a 90-degree angled mirror. The two 90-degree angled mirrors are arranged to be symmetrical about a center of the disk. Another reflecting strip comprises four 90-degree angled mirrors arranged to be symmetrical with respect to the center of the disk as well. A free zone is formed around the center between the two reflecting strips so as not to cause interferences therebetween.
The light transmitting/receiving sub-assembly comprises first and second linear arrays of collimators corresponding to the reflecting strips and thus are perpendicular to each other. Each array comprises equally-spaced collimators.
In a first position, light from the odd-numbered collimators of the first collimator array is reflected by the corresponding mirrors of the corresponding first reflecting strip to the corresponding even-numbered collimators in a non-sequential fashion. At the same time, light transmitting from the odd-numbered collimators of the second collimator array enters the corresponding even-numbered collimators after being reflected by the corresponding four 90-degree angled mirrors of the corresponding second reflecting strip in a sequential fashion.
In a second position, where the reflecting means is rotated 90 degrees relative to the light transmitting/receiving sub-assembly, whereby the first collimator array is opposite to the second reflecting strip while the second collimator array is opposite to the first reflecting strip. Light from the odd-numbered collimators of the first collimator array will be reflected by the four 90-degree angled mirrors of the second reflecting strip, and thus switched to the corresponding even-numbered collimators in exactly the same way as that of the first collimator array and the first reflecting strip in the first position. Similarly, the light reflecting paths between the second collimator array and the first reflecting strip replicate those between the first collimator array and the first reflecting strip originally occurred in the first position. Due to the difference between the output sequences of the light beams, a switching operation is achieved.